Valve mechanism for rock drills



Sept. 14, 1937. A. R. MACK 8 VALVE MECHANISM FOR ROCK DRILLS Filed April26, 1937 59 9 I 47 6'1 I J5 2 -2 Alba fields.

H I S ATTORNEY.

Patented Sept. 14, 1937 UNETED STATES VALVE MECHANISM FOR ROCK DRILLSAlbert R. Mack, Phillipsburg, N. J., assignor to Ingersoll-Rand Company,Jersey City, N. J., a

corporation of New Jersey 1 Application April 26, 1937, Serial No.138,967

4 Claims.

This invention relates to rock drills, and more particularly to a valvemechanism for distributing the pressure fluid to the percussive elementof the rock drill.

The objects of the invention areto obtain a heavy blow of thepercussiveelement against the working implement, to minimize the power cost ofoperating the tool, and to effect a rapid distribution of pressurefluid-and a consequent rapid action of the percussive element.

Other objects will be in part obvious and in part pointed outhereinafter.

In the drawing accompanying this specification and in which similarreference numerals refer to similar parts,

Figures 1 and 2 are longitudinal views, in sec tion, showing the valvesin the different limiting positions which they will occupy in operation.

Referring more particularly to the drawing, designates a cylinder of arock drill having a piston chamber 2| to accommodate a reciprocatoryhammer piston 22 which controls a free exhaust port 23 for the pistonchamber 2 A closure is provided for the front end of the piston chamberin the form of a front cylinder washer 24 and a back cylinder washer 25per-- forms a like function for the rear end of the piston chamber 2!.The back cylinder washer 25 is arranged within an enlarged bore 26 inthe rear end of the cylinder 20 and serves as a seat for valve mechanismcomprising, among other elements, a valve chest 2'! which may be clampedin position by a back head 28 and the usual side bolts (not shown).

In the form of the invention illustrated, a pair of plates 29 and 30 areinterposed between the back head 28 and the valve chest 2'! and bored toreceive an end of a bushing 3| of which the opposite end extends intothe back cylinder washer 25. The internal surface of the bushing 3|serves as a bearing for a rifle bar 32, wherewith the piston 22 isslidably interlocked, and the rifle bar 32 may be provided with theusual pawl and ratchet devices for eifecting step-by-step rotarymovement of the piston 22 and thus, through suitable mechanism (notshown), of a working implement which the piston is intended to actuate.

The valve chest 2'! comprises an intermediate plate 33 and end plates 34and 35 seating against the plate 30 and the back cylinder washer 25,respectively. The plates 33, 34 and 35 are suitably bored to form aValve chamber 36 for which the periphery of the bushing 3| serves as aninner bounding surface. Intermediate the ends of the valve chamber 36,and located in the plate 33, is an annular groove 31 into which pressurefluidis introduced from a source of supply by a passage 38 extendingthrough the plates 29, 30, 3.4 and 33.

In the portions of the valve chamber lying forwardly and rearwardly ofthe groove 31 are valves 39- and 40, respectively, for controlling theadmission of pressure fluid to-the ends of the piston chamber 2l. Thevalves are of substantially the same conformation, each being of thesleeve type encircling the bushing 3| and having a peripheral flange 4|intermediate its ends. There are, however, essential diiferences in themanner of application of the forces controlling the action of thevalves. Each valve is provided with a series of longitudinal passages 42which extend entirely through the wall of the valve and are in constantcommunication with the annular groove 37.

The pressure fluid passing through the passages 42 of the valve passes,in the open position of said valve, through a channel 43 defined by theplates 29 and 33, thence through an inlet passage 44 to the front end ofthe piston chamber 2|, and the pressure fluid flowing through thepassages 42 of the valve 39 flows through the front end of the valvechamber 36, an annular groove 45 in the plate 35 and through an inletport or ports 46, in the back cylinder washer 25, into the rear end ofthe piston. chamber 2|. The passages 42 are off-set with respect to theports 46 and, in the closed position of the valve 39, are sealed by theback cylinder wash-er 25.

The inlet opening 4'! of the channel 43 is, likewise, off-set withrespect to the ports 42 in the valve 43 and thus, in the closed positionof said valve, the plate 30 will serve to seal the rear ends of theadjacent passages 42.

Preferably, a small leak port 48 is formed in the back cylinder washer25 to assure a constant slight admission of pressure fluid into the rearend of the piston chamber to facilitate and assure starting of thehammer piston 22 at the beginning of each period of operation.

The opposing surfaces of the flange 4| of the valve 39 constitute frontand rear actuating surfaces 49 and 50 Which are intermittently subjectedto pressure fluid valved thereto by the piston 22. Pressure fluid isconveyed to the actuating surface 49 by a kicker passage 5| leading fromthe piston chamber2| at a point forwardly of the exhaust port 23 to thegroove 52 containing the flange 4|. A second kicker passage 53 leadsfrom a point in the piston chamber rearwardly of the exhaust port 23 tothe rearward end of the groove 52.

The portion of the valve 39 lying forwardly of. the flange 4| is oflarger diameter than the rearward portion and the front or end surfaceof the valve constitutes a holding surface 54 which is exposed topressure fluid flowing thereover to the inlet passage 46 for holding thevalve 39 in its rearmost limiting position. Similarly, the surface ofthe valve confronting the groove 31 serves as a holding surface 55against which pressure fluid constantly acts. Such pressure fluidassists in shifting the valve 39 forwardly and is the force that holdsthe valve in its foremost limiting position.

The opposing end surfaces of. the valve 40 also constitute holdingsurfaces 56 and 51. That designated 56 is the surface of larger area andis constantly exposed to pressure fluid in the groove 31. The surface56, moreover, serves as an actuating surface against which the pressureacts for shifting the valve rearwardly to close communication betweensupply and the front inlet passage 44.

An opposing actuating surface 58 is located on the rear end of theflange M of the valve 40, and a passage 59 leads from the rear end ofthe groove 69 containing the flange 4| to a point near the 7 forward endof the pistonchamber 2|. More specifically, the passage 59 is a tripperpassage and pressure fluid is constantly introduced thereinto by a leakport 6| leading from the groove 37. The front end of the groove 60 isvented to the atmosphere through a passage 62 extending through thevalve chest and the cylinder 20.

The operation of the device is as follows: With the valves and thepiston in the rearmost limiting positions, as illustrated in Figure 1,the passages 42 of the valve 49 are sealed by the plate 30 and the valve40 is held immovable by the pressure fluid acting against the surface56. Pressure fluid then flows through the passages 42 of the valve 39into the front end of the valve chamber 36, thence through the groove 45and the inlet passages 46 into the rear end of the piston chamber 21 anddrives the piston 22 forwardly on its working stroke. The valve 39 isheld in the open position described by the pressure fluid acting againstthe holding surface 54.

During its forward movement the piston uncovers the kicker passage 53.Pressure fluid then flows into the groove 52 and, acting against theactuating surface 50, throws the valve 39 forwardly to cut off the flowof. pressure fluid into the rear end of the piston chamber. This forceis augmented by the pressure fluid acting constantly against the surface55 and which serves, after the valve has been shifted, to hold the valveseated against the back cylinder washer 25.

Immediately after uncovering the kicker passage 53 the piston uncoversthe free exhaust port 23 to communicate the rear ends of the pistonchamber and the groove 52 to the atmosphere. Simultaneously with theuncovering of the exhaust port 23, or immediately thereafter, the pistoncovers the tripper passage 59. The pressure fluid flowing into thetripper passage 59 will then be entrapped therein and act against theactuating surface 58 and move the valve 40 forwardly. a

In the new position of the valve 40 pressure fluid flows from the groove31 through the passages 42 of the unseated valve, thence through thechannel 43 and the inlet passage 44 into the front end of the pistonchamber 2| to return the piston 22 to its initial position. During thecharging of the front end of the piston chamber the valve 49 is heldimmovable by the pressure fluid flowing over the holding surface 51 andthat acting against the actuating surface 58.

The valve 49 remains in the open position until the front end of thepiston 22 again uncovers the exhaust port 23, whereupon the pressurefluid employed for actuating the piston and that acting against theactuating surface 58 is exhausted to the atmosphere. The pressure fluidacting against the surface 56 will then immediately shift the valve 49against the plate 30 and cut off communication between the inlet passage44 and the groove 31. However, immediately before the piston uncoversthe exhaust port 23, during the rearward stroke of the piston, it willuncover the kicker passage 5| and pressure fluid then flows into thefront end of the groove against the actuating surface 49 and lift thevalve to again establish communication between the source of supply andthe rear end of the piston chamber.

I claim: 7, V

1. In a fluid actuated rock drill, the combination of acasing having apiston chamber and a piston therein, an exhaust port for the pistonchamber, a valve chest having a valve chamber, inlet passages leadingfrom the valve chamber to the piston chamber, valves in the valvechamber' for controlling the inlet passages, opposed actuating surfaceson one valve of which one actuating surface is constantly exposed andanother actuating surface intermittently exposed to pressure fluid forthrowing the valve, and

opposed actuating surfaces on the other valve intermittently exposed topressure fluid for throwing thesaid other valve. V

2. In a fluid actuated rock drill, the combination of a casing having apiston chamber and a piston therein, an exhaust port for the pistonchamber, a valve chest having a valve chamber, inlet passages leadingfrom the valve chamber to the piston chamber, a valve in the valvechamber to control an inlet passage and having an actuating surfaceintermittently exposed to pres sure fluid for throwing the valve to onelimiting position, a holding surface on the valve intermittently exposedto pressure fluid for holding the valve in such position, an opposedactuating surface on the valve constantly exposed to pressure fluid forthrowing the valve to another limiting position and for holding thevalve, a second valve in the valve chamber for controlling an otherinlet passage andhaving opposed actuating surfaces intermittentlyexposed to pressure fluid for throwing said second valve, and opposedholdin'g'surfaces on said second valve exposed to pressure fluid forholding said second valve.

3. In a fluid actuated rock drill, the combination of a casing having apiston chamber and a piston therein, an exhaust port for the pistonchamber, a valve chest having a valve chamber, inlet passages leadingfrom the valve chamber to the piston chamber, a valve in the valvechamber to control an inlet passage, an actuating surface on the valveintermittently exposed to pressure fluid for throwing the valve to onelimiting position, a holding surface on the valve intermittently exposedto pressure fluid for holding the valve in such position, an opposedactuating surface on the valve of greater area than the holding surfaceand being constantly exposed to pressure fluid for throwing the valve 4'to another limiting position and for holding the valve, a second valvein the valve chamber for controlling another inlet passage and havingopposed actuating surfaces intermittently exposed to pressure fluid forthrowing said second valve, a pressure surface on the said second valveconstantly exposed to pressure fluid for throwing and holding saidsecond valve, and a holding surface on said second valve of greater areathan the pressure surface and being intermittently exposed to pressurefluid for holding the said second valve.

4. In a fluid actuated rock drill, the combination of a casing having apiston chamber and a piston therein, an exhaust port for the pistonchamber, a valve chest having a valve chamber, inlet passages leadingfrom the valve chamber to the piston chamber, a valve in the valvechamber to control an inlet passage, an actuating surface on the valveintermittently exposed to pressure fluid for throwing the valve to admitpressure fluid to one inlet passage, a holding surface exposed topressure fluid flowing to the inlet passage for holding the valve, anopposed actuating surface on the valve exposed constantly to pressurefluid for returning and holding the valve and being of greater area thanthe holding surface, a second valve in the valve chamber to controlanother inlet passage and having opposed actuating surfacesintermittently exposed to pressure fluid for throwing said second valve,a holding surface on said second valve exposed intermittently topressure fluid for holding said second valve in position to admitpressure fluid to the associated inlet passage, and an opposed holdingsurface on said second valve of smaller area than the last mentionedholding surface constantly exposed to pressure fluid to assist inthrowing the valve for cutting off the flow of pressure fluid to theassociated inlet passage and for holding the valve.

ALBERT R. MACK.

